Biodegradation of nitrate and p-bromophenol using hydrogen-based membrane biofilm reactors in parallel

Area of Science:

• Environmental Science
• Microbiology
• Chemical Engineering

Background:

• P-bromophenol (4-BP) is a toxic halogenated organic compound posing challenges for conventional water treatment.
• Existing methods for 4-BP removal are often inefficient, costly, and struggle with complete mineralization.

Purpose of the Study:

• To investigate the efficacy of a membrane biofilm reactor (MBfR) utilizing hydrogen as an electron donor for 4-BP degradation.
• To elucidate the degradation pathway and microbial community dynamics involved in 4-BP removal under specific operational conditions.

Main Methods:

• Utilized a hydrogen-fed membrane biofilm reactor (H2-MBfR) for treating water contaminated with 4-BP and nitrates.
• Conducted long-term operational experiments varying nitrate and 4-BP concentrations, and hydrogen partial pressure.
• Analyzed microbial community diversity using 16S rRNA gene sequencing.

Main Results:

• Achieved rapid and complete removal (approx. 100%) of 4-BP up to 20 mg/L with minimal intermediate accumulation.
• Demonstrated simultaneous reduction of 10 mg/L nitrate under anaerobic conditions.
• Identified *Thauera* as the dominant genus responsible for 4-BP degradation, with enhanced related enzyme gene expression.

Conclusions:

• The H2-MBfR system offers an efficient, cost-effective, and environmentally friendly bioremediation strategy for co-contaminants like 4-BP and nitrates.
• Microbial degradation, particularly by *Thauera*, plays a crucial role in the removal of 4-BP in this anaerobic system.
• This approach presents a promising solution for treating contaminated water bodies.